CINCINNATI -- They were one swing, one run or one pitch away. Yet again.

And yet again, Yoenis Cespdes provided that swing, hitting a two-run homer in the eighth inning as the Boston Red Sox edged the Cincinnati Reds, 3-2.

Cespedes, acquired from the Oakland A's on July 31 in the trade that sent Jon Lester out of town, has already made his presence felt, providing a lead-changing home run in each of the Red Sox's last two games.

"He's a threat every time he steps to the plate," manager John Farrell said.

The 2014 Red Sox will be remembered for taking the best offense in baseball and turning it into one of the the worst; for having decisions to make, contracts to write, and yet taking too long to complete them. They'll end up losing a lot of games, too many to make them relevant.

And yet in many of their failing encounters, they've been so close to winning.

Their anemic offense can be explained by their unusually-low number of extra-base hits. With power on their side, the Red Sox had the edge in 2013, when they led baseball in slugging percentage and runs scored. Without power in 2014, as they've been last in the American League in slugging and runs, the storyline has been repeated over and over: They had opportunities, but didn't cash in.

Consider this: Collecting three extra-base hits in a game shouldn't be groundbreaking, but the Red Sox have done it just 48 percent of the time in 2014, their lowest frequency since 1994. In 35 seasons since 1980, only four times have they failed to collect at least three extra-base hits in at least half of their games.

The Red Sox can get on base all day long, but they hadn't been scoring. Power is the differentiator in today's game, because it's so rare.

"It’s a middle of the order bat," Farrell said. Cespedes "gives us a certain presence in the middle of the order, and a much needed one. And he’s shown on all sides of the baseball that he’s a complete player."

Tuesday night, the Red Sox beat the Reds, a slightly-above-average team. The Red Sox, well-below average, had just come off beating the Anaheim Angels, well-above average, in a three-game series.

In each of their last three wins, they've homered.

"Having that ability to change the game with one swing of the bat is important for us," Farrell said.

The pitch before Cespedes homered was a high-and-tight 95-mph fastball that nearly took his head off. Cespedes stared down the pitcher, Jonathan Broxton, then took him 433 feet to center field.

"A lot of times pitchers think when you get a pitch thrown high and tight, you're going to back off and get a little flustered," Cespedes said. "But that's not how I am. I was able to focus myself even more after that pitch and get a good pitch to hit."

Cespedes has 19 home runs on the season. He's reached base in all nine games he's played with the Red Sox.

His ability to shake off the pitch that almost hit him in the head impressed his manager.

"At field level you’re always looking to respond to certain things," Farrell said. "And I’m not saying the pitch was intentional, he threw the ball up and in on him. But he threw the ball up over the plate, gets one and squares it up and it’s the difference in this tonight."

Cespedes' two-run homer turned a 2-1 deficit into a 3-2 lead, earning reliever Tommy Layne his first career win with the Red Sox.

Joe Kelly was just as deserving of the decision.

Kelly mirrored Clay Buchholz's most recent start, allowing two runs in the first inning and then submitting a dominant performance the rest of the way, allowing just three hits and one walk over the next five innings. Kelly, the above-average pitcher brought over from the St. Louis Cardinals as part of the John Lackey trade, has allowed three runs over 13 innings in his first two starts with the Red Sox.